In the present work, the molecular structures of two new synthesized dyes：（4,6-dimethylpyrimidin-2-ylamino）（5-p-tolylisoxazol-3-yl）methanol（PS-1） and N-（4,6-dimethylpyrimidin-2-yl）-5-phenylisoxazole-3-carboxa...In the present work, the molecular structures of two new synthesized dyes：（4,6-dimethylpyrimidin-2-ylamino）（5-p-tolylisoxazol-3-yl）methanol（PS-1） and N-（4,6-dimethylpyrimidin-2-yl）-5-phenylisoxazole-3-carboxamide（PS-2）, have been investigated using density functional theory（DFT） in dimethylformamide（DMF） for the first time. The electronic spectra of new dyes in a DMF solvent were carried out by time dependent density functional theory（TD-DFT） method. After quantum-chemical calculations two new dyes for the optoelectronic applications were synthesized. FT-IR spectra of the title compounds are recorded and discussed. NucleusIndependent Chemical Shifts（NICS） calculations have also been carried out for the title compounds. The computed absorption spectral data of the title compounds are in good agreement with the experimental data, thus allowing an assignment of the UV spectra. The HOMO and LUMO molecular orbitals, excitation energies and oscillator strengths for the dyes have also been calculated and presented.展开更多
Rocky desertification has become a major environmental issue in the karst region of southwestern China.Karst rocky desertification was more severe in regions of limestone soil than in adjacent regions of other soils,d...Rocky desertification has become a major environmental issue in the karst region of southwestern China.Karst rocky desertification was more severe in regions of limestone soil than in adjacent regions of other soils,despite the relatively higher soil organic matter(SOM)content in limestone soil.The underlying mechanism remains ambiguous.We speculated that the geochemical characteristics of limestone soils in the karst region plays an essential role,especially the high calcium content of limestone soil.To test this hypothesis,we collected limestone soil samples from a limestone soil profile in the southwestern China karst region and extracted humic acid(HA)from these limestone soil samples.We investigated the interaction of Ca^(2+)and three HA samples on a joint experimental platform,which consists of an automatic potentiometric titrator,a UV–visible spectrometer,and a Fluorescence spectrometer.HA solutions were titrated by Ca^(2+)and optical spectra of the HA solutions were monitored during the titration experiments.The results indicated that:(1)the interaction of Ca^(2+)and HA is a combined process of adsorption and complexation.Adsorption dominated the overall distribution behavior of Ca^(2+),which could be fit by Langmuir and Freundlich isotherm models.Complexation was distinguished only when the concentration of Ca2+is low;(2)the changes of UV–visible spectroscopy and excitation–emission matrix fluorescencespectroscopy spectra of HA samples when they were binding with Ca^(2+)implied the apparent molecular size and structure of HA became larger and more complex;(3)the combination of Ca^(2+)and HA plays an important role in the SOM preservation of limestone soils but the stability of the Ca–HA association was relatively weak.The present study draws attention to maintaining the relatively higher Ca^(2+)concentration in limestone soils in ecologic restoration attempts in karst regions.展开更多
A new coordination polymer [Cu2(OH)(nbta)(tib)(H2 O)2]n(1, H3 nbta = 5-nitro-1,2,3-benzenetricarboxylic acid, tib = 1-(4 H-1,2,4-triazol-4-yl)-4-(imidazol-1-yl)benzene) constructed from dimeric Cu(Ⅱ) units has been s...A new coordination polymer [Cu2(OH)(nbta)(tib)(H2 O)2]n(1, H3 nbta = 5-nitro-1,2,3-benzenetricarboxylic acid, tib = 1-(4 H-1,2,4-triazol-4-yl)-4-(imidazol-1-yl)benzene) constructed from dimeric Cu(Ⅱ) units has been synthesized under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction analysis. The compound crystallizes in monoclinic system, space group I2/c, with a = 17.8474(9), b = 11.7588(6), c = 21.9221(11) ?, β = 104.419(5)°, V = 4455.7(4) ?3 and Z = 8. Compound 1 is a three-dimensional structure constructed from dimeric Cu(Ⅱ) units and presents a 2-nodal(3,5)-connected net. Moreover, the thermal stability and solid UV-Vis absorption spectra have been investigated.展开更多
The doping reaction of polyaniline with camphor sulfonic acid (CSAH) in different organic solvents was studied by UV Vis spectroscopy. The experimental results show that the polaron band of the species was shifted to ...The doping reaction of polyaniline with camphor sulfonic acid (CSAH) in different organic solvents was studied by UV Vis spectroscopy. The experimental results show that the polaron band of the species was shifted to shorter wavelength when polyaniline was doped with CSAH in N methyl 2 pyrrolidione (NMP) solvent, while the red shift of polaron band was observed when it was in N, N dimethylformamide (DMF). It indicates that the influence of different processing solvents on the doping property of polyaniline is greatly different. N methyl 2 pyrrolidione is a good solvent for polyaniline, polyaniline chain is unfolded in it. The interaction of NMP with CSAH is so strong that the resulting product is apt to dedoping, while the solubility of polyaniline in DMF is relatively low and polyaniline chain is in partly folded state. Thus the doping reaction is kinetically disadvantageous but thermodynamically advantageous.展开更多
The adsorption behaviour has been studied using in situ FTIR and UV/Vis spectroscopy,voltammetry,AC impedance and polential step methods.The results show that cytochrome c can be irreversibly adsorbed on the gold surf...The adsorption behaviour has been studied using in situ FTIR and UV/Vis spectroscopy,voltammetry,AC impedance and polential step methods.The results show that cytochrome c can be irreversibly adsorbed on the gold surface in a complete monolayer and the adsorbed layer can mediate the redox reaction of cytochrome c in the solotiorr but not ail adsorbed cytochrome c molecules would play this role.展开更多
In the given research,the molecular structures of two new compounds,4-((E)-3-(dimethylamino)styryl)-6-((E)-4-(dimethylamino)styryl)pyrimidine-2-amine(PM-1)and N-(4-((E)-3-(dimethylamino)styryl)-6-((E)-4-(dimethylamino...In the given research,the molecular structures of two new compounds,4-((E)-3-(dimethylamino)styryl)-6-((E)-4-(dimethylamino)styryl)pyrimidine-2-amine(PM-1)and N-(4-((E)-3-(dimethylamino)styryl)-6-((E)-4-(dimethylamino)styryl)pyrimidine-2-yl)-4,6-dichloro 1,3,5-1,3,5-triazin-2-amine(PM-2),have been studied with the use of density functional theory(DFT/B3LYP/MidiX)in dimethylformamide(DMF)for the first time.The electronic spectra of the new compounds in a DMF solvent were carried out by temporally dependent density functional theory(TD-DFT)method.The computed absorption spectral data of the title compounds are in good agreement with the experimental data,thus allowing an assignment of the UV/Vis spectra.The equilibrium geometry,the HOMO and LUMO molecular orbitals,excitation energies,oscillator strengths and Natural Bond Orbital(NBO)analysis for the molecules have also been calculated and presented.FT-IR spectra of the title molecules are recorded and discussed.The electron location function(ELF),localized orbital locator(LOL)and quantum theory of atoms in molecules(QTAIM)analyses were also carried out.On the basis of polyvinyl alcohol(PVA)and synthesized molecules,polarizer for UV/Vis region of the spectrum has been developed.展开更多
The opticai properties of C,, chemicaiiy modified poiystyrene(C,, -PS copolymer) and the parent polystyrene (PS) films have been investigated.Addition of bulky C,, moiety, a special functional group, to the polystyren...The opticai properties of C,, chemicaiiy modified poiystyrene(C,, -PS copolymer) and the parent polystyrene (PS) films have been investigated.Addition of bulky C,, moiety, a special functional group, to the polystyrene by anovel organometallic reaction modified considerably the optical property of theparent polystyrene. The lattice periodicity of pure PS film is subject to someperturbation or distortion in varying degrees due to the covalent attachInent of bulkyC,, moiety to the polymer backbone. C,,-PS copolymer possesses a new energy ba-ndstructure with indirect forbidden band when compared with the parent PS.展开更多
In this work,the octaethyl-porphyrins with different central metals(M-OEP,M=Ni,VO,Cu,Co)were used to investigate the ground-state molecular structure,electron distribution and UV-spectra properties on molecular level ...In this work,the octaethyl-porphyrins with different central metals(M-OEP,M=Ni,VO,Cu,Co)were used to investigate the ground-state molecular structure,electron distribution and UV-spectra properties on molecular level by density functional theory(DFT).The results showed that the calculation structure parameters of metalloporphyrins agreed well with the experimental value.According to the Natural Bond Orbital(NBO)analysis,the charge distribution of different metalloporphyrins was found that the charge values of the central metal M decreased with the order of VO<Ni<Co<Cu,while the bonding strength between M and the coordinating atom N was VO>Ni>Co>Cu.At the same time,the frontier molecular orbital calculations showed that the SOMO energy of VO(OEP)molecules in the open-shell system was higher than that of Co(OEP)and Cu(OEP),which means that its UV absorption characteristic peak would be red-shifted.In addition,the IEFPCM model of Time-dependent Density functional theory(TD-DFT)was further utilized to simulate the four substance in toluene solution:Co(OEP),Ni(OEP),Cu(OEP)and VO(OEP),and the Soret band peaks were calculated respectively as:382 nm,383 nm,391 nm and 401 nm.Furthermore,the quantitative simulation analysis of metalloporphyrins was combined with experimental data.It could be found that the location rules of the four kinds of metalloporphyrins calculated absorption characteristic peaks were consistent with the experimental ones,and the relative errors of each peak were within 3%.These methods used above provide a theoretical path for analyzing and identifying unknown porphyrin compounds in petroleum.展开更多
Amphotericin B(AmB)is an amphiphilic drug commonly formulated in liposomes and administered intravenously to treat systemic fungal infections.Recent studies on the liposomal drug product have shed light on the AmB agg...Amphotericin B(AmB)is an amphiphilic drug commonly formulated in liposomes and administered intravenously to treat systemic fungal infections.Recent studies on the liposomal drug product have shed light on the AmB aggregation status in the bilayer,which heat treatment(curing)modifies.Although toxicity was found related to aggregation status-loose aggregates significantly more toxic than tight aggregates-the precise mechanism linking aggregation and toxicitywas notwell understood.This study directlymeasured drug release rate fromvarious AmB liposomal preparations made with modified curing protocols to evaluate correlations among drug aggregation state,drug release,and in vitro toxicity.UV–Vis spectroscopy of these products detected unique curing-induced changes in the UV spectral features:a∼25nm blue-shift of the main absorption peak(λ_(max))in aqueous buffer and a decrease in the OD_(346)/OD_(322) ratio upon thermal curing,reflecting tighter aggregation.In vitro release testing(IVRT)data showed,by applying and fitting first-order release kinetic models for one or two pools,that curing impacts two significant changes:a 3–5-fold drop in the overall drug release rate and a ten-fold decrease in the ratio between the loosely aggregated and the tightly aggregated,more thermodynamically stable drug pool.The kinetic data thus corroborated the trend independently deduced from the UV–Vis spectral data.The in vitro toxicity assay indicated a decreased toxicity with curing,as shown by the significantly increased concentration,causing half-maximal potassium release(TC50).The data suggest that the release of AmB requires dissociation of the tight complexes within the bilayer and that the reduced toxicity relates to this slower rate of dissociation.This study demonstrates the relationship between AmB aggregation status within the lipid bilayer and drug release(directly measured rate constants),providing a mechanistic link between aggregation status and in vitro toxicity in the liposomal formulations.展开更多
基金supported by the National Academy of Sciences of Belarus
文摘In the present work, the molecular structures of two new synthesized dyes：（4,6-dimethylpyrimidin-2-ylamino）（5-p-tolylisoxazol-3-yl）methanol（PS-1） and N-（4,6-dimethylpyrimidin-2-yl）-5-phenylisoxazole-3-carboxamide（PS-2）, have been investigated using density functional theory（DFT） in dimethylformamide（DMF） for the first time. The electronic spectra of new dyes in a DMF solvent were carried out by time dependent density functional theory（TD-DFT） method. After quantum-chemical calculations two new dyes for the optoelectronic applications were synthesized. FT-IR spectra of the title compounds are recorded and discussed. NucleusIndependent Chemical Shifts（NICS） calculations have also been carried out for the title compounds. The computed absorption spectral data of the title compounds are in good agreement with the experimental data, thus allowing an assignment of the UV spectra. The HOMO and LUMO molecular orbitals, excitation energies and oscillator strengths for the dyes have also been calculated and presented.
基金supported by the National Natural Science Foundation of China (U1701241, U1612441,41773147, and 41273149)the Science Foundation of Guizhou(20113109) 。
文摘Rocky desertification has become a major environmental issue in the karst region of southwestern China.Karst rocky desertification was more severe in regions of limestone soil than in adjacent regions of other soils,despite the relatively higher soil organic matter(SOM)content in limestone soil.The underlying mechanism remains ambiguous.We speculated that the geochemical characteristics of limestone soils in the karst region plays an essential role,especially the high calcium content of limestone soil.To test this hypothesis,we collected limestone soil samples from a limestone soil profile in the southwestern China karst region and extracted humic acid(HA)from these limestone soil samples.We investigated the interaction of Ca^(2+)and three HA samples on a joint experimental platform,which consists of an automatic potentiometric titrator,a UV–visible spectrometer,and a Fluorescence spectrometer.HA solutions were titrated by Ca^(2+)and optical spectra of the HA solutions were monitored during the titration experiments.The results indicated that:(1)the interaction of Ca^(2+)and HA is a combined process of adsorption and complexation.Adsorption dominated the overall distribution behavior of Ca^(2+),which could be fit by Langmuir and Freundlich isotherm models.Complexation was distinguished only when the concentration of Ca2+is low;(2)the changes of UV–visible spectroscopy and excitation–emission matrix fluorescencespectroscopy spectra of HA samples when they were binding with Ca^(2+)implied the apparent molecular size and structure of HA became larger and more complex;(3)the combination of Ca^(2+)and HA plays an important role in the SOM preservation of limestone soils but the stability of the Ca–HA association was relatively weak.The present study draws attention to maintaining the relatively higher Ca^(2+)concentration in limestone soils in ecologic restoration attempts in karst regions.
基金supported by the National Natural Science Foundation of China(21401097)
文摘A new coordination polymer [Cu2(OH)(nbta)(tib)(H2 O)2]n(1, H3 nbta = 5-nitro-1,2,3-benzenetricarboxylic acid, tib = 1-(4 H-1,2,4-triazol-4-yl)-4-(imidazol-1-yl)benzene) constructed from dimeric Cu(Ⅱ) units has been synthesized under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction analysis. The compound crystallizes in monoclinic system, space group I2/c, with a = 17.8474(9), b = 11.7588(6), c = 21.9221(11) ?, β = 104.419(5)°, V = 4455.7(4) ?3 and Z = 8. Compound 1 is a three-dimensional structure constructed from dimeric Cu(Ⅱ) units and presents a 2-nodal(3,5)-connected net. Moreover, the thermal stability and solid UV-Vis absorption spectra have been investigated.
文摘The doping reaction of polyaniline with camphor sulfonic acid (CSAH) in different organic solvents was studied by UV Vis spectroscopy. The experimental results show that the polaron band of the species was shifted to shorter wavelength when polyaniline was doped with CSAH in N methyl 2 pyrrolidione (NMP) solvent, while the red shift of polaron band was observed when it was in N, N dimethylformamide (DMF). It indicates that the influence of different processing solvents on the doping property of polyaniline is greatly different. N methyl 2 pyrrolidione is a good solvent for polyaniline, polyaniline chain is unfolded in it. The interaction of NMP with CSAH is so strong that the resulting product is apt to dedoping, while the solubility of polyaniline in DMF is relatively low and polyaniline chain is in partly folded state. Thus the doping reaction is kinetically disadvantageous but thermodynamically advantageous.
文摘The adsorption behaviour has been studied using in situ FTIR and UV/Vis spectroscopy,voltammetry,AC impedance and polential step methods.The results show that cytochrome c can be irreversibly adsorbed on the gold surface in a complete monolayer and the adsorbed layer can mediate the redox reaction of cytochrome c in the solotiorr but not ail adsorbed cytochrome c molecules would play this role.
基金supported by the National Academy of Sciences of Belarus
文摘In the given research,the molecular structures of two new compounds,4-((E)-3-(dimethylamino)styryl)-6-((E)-4-(dimethylamino)styryl)pyrimidine-2-amine(PM-1)and N-(4-((E)-3-(dimethylamino)styryl)-6-((E)-4-(dimethylamino)styryl)pyrimidine-2-yl)-4,6-dichloro 1,3,5-1,3,5-triazin-2-amine(PM-2),have been studied with the use of density functional theory(DFT/B3LYP/MidiX)in dimethylformamide(DMF)for the first time.The electronic spectra of the new compounds in a DMF solvent were carried out by temporally dependent density functional theory(TD-DFT)method.The computed absorption spectral data of the title compounds are in good agreement with the experimental data,thus allowing an assignment of the UV/Vis spectra.The equilibrium geometry,the HOMO and LUMO molecular orbitals,excitation energies,oscillator strengths and Natural Bond Orbital(NBO)analysis for the molecules have also been calculated and presented.FT-IR spectra of the title molecules are recorded and discussed.The electron location function(ELF),localized orbital locator(LOL)and quantum theory of atoms in molecules(QTAIM)analyses were also carried out.On the basis of polyvinyl alcohol(PVA)and synthesized molecules,polarizer for UV/Vis region of the spectrum has been developed.
文摘The opticai properties of C,, chemicaiiy modified poiystyrene(C,, -PS copolymer) and the parent polystyrene (PS) films have been investigated.Addition of bulky C,, moiety, a special functional group, to the polystyrene by anovel organometallic reaction modified considerably the optical property of theparent polystyrene. The lattice periodicity of pure PS film is subject to someperturbation or distortion in varying degrees due to the covalent attachInent of bulkyC,, moiety to the polymer backbone. C,,-PS copolymer possesses a new energy ba-ndstructure with indirect forbidden band when compared with the parent PS.
基金the supports from the National Natural Science Foundation of China(21822810,21476260,and 21838011).
文摘In this work,the octaethyl-porphyrins with different central metals(M-OEP,M=Ni,VO,Cu,Co)were used to investigate the ground-state molecular structure,electron distribution and UV-spectra properties on molecular level by density functional theory(DFT).The results showed that the calculation structure parameters of metalloporphyrins agreed well with the experimental value.According to the Natural Bond Orbital(NBO)analysis,the charge distribution of different metalloporphyrins was found that the charge values of the central metal M decreased with the order of VO<Ni<Co<Cu,while the bonding strength between M and the coordinating atom N was VO>Ni>Co>Cu.At the same time,the frontier molecular orbital calculations showed that the SOMO energy of VO(OEP)molecules in the open-shell system was higher than that of Co(OEP)and Cu(OEP),which means that its UV absorption characteristic peak would be red-shifted.In addition,the IEFPCM model of Time-dependent Density functional theory(TD-DFT)was further utilized to simulate the four substance in toluene solution:Co(OEP),Ni(OEP),Cu(OEP)and VO(OEP),and the Soret band peaks were calculated respectively as:382 nm,383 nm,391 nm and 401 nm.Furthermore,the quantitative simulation analysis of metalloporphyrins was combined with experimental data.It could be found that the location rules of the four kinds of metalloporphyrins calculated absorption characteristic peaks were consistent with the experimental ones,and the relative errors of each peak were within 3%.These methods used above provide a theoretical path for analyzing and identifying unknown porphyrin compounds in petroleum.
基金financially supported by the Offi ce of Research and Standards, Office of Generic Drugs, CDER at the FDA (75F40120C00055)
文摘Amphotericin B(AmB)is an amphiphilic drug commonly formulated in liposomes and administered intravenously to treat systemic fungal infections.Recent studies on the liposomal drug product have shed light on the AmB aggregation status in the bilayer,which heat treatment(curing)modifies.Although toxicity was found related to aggregation status-loose aggregates significantly more toxic than tight aggregates-the precise mechanism linking aggregation and toxicitywas notwell understood.This study directlymeasured drug release rate fromvarious AmB liposomal preparations made with modified curing protocols to evaluate correlations among drug aggregation state,drug release,and in vitro toxicity.UV–Vis spectroscopy of these products detected unique curing-induced changes in the UV spectral features:a∼25nm blue-shift of the main absorption peak(λ_(max))in aqueous buffer and a decrease in the OD_(346)/OD_(322) ratio upon thermal curing,reflecting tighter aggregation.In vitro release testing(IVRT)data showed,by applying and fitting first-order release kinetic models for one or two pools,that curing impacts two significant changes:a 3–5-fold drop in the overall drug release rate and a ten-fold decrease in the ratio between the loosely aggregated and the tightly aggregated,more thermodynamically stable drug pool.The kinetic data thus corroborated the trend independently deduced from the UV–Vis spectral data.The in vitro toxicity assay indicated a decreased toxicity with curing,as shown by the significantly increased concentration,causing half-maximal potassium release(TC50).The data suggest that the release of AmB requires dissociation of the tight complexes within the bilayer and that the reduced toxicity relates to this slower rate of dissociation.This study demonstrates the relationship between AmB aggregation status within the lipid bilayer and drug release(directly measured rate constants),providing a mechanistic link between aggregation status and in vitro toxicity in the liposomal formulations.
